In a previous study, researchers at the University of Science and Technology of China demonstrated how injecting nanoparticles into the retinas of mice allowed them to see in the near-infrared range (NIR). This is a range of light not normally detectable by mammals, which tends to cap out beneath to 700-nanometer (nm) wavelength. NIR light travels in wavelengths between 700 nm and 2,500 nm and while it can be felt as heat, we can't see it.

Looking to see if they could develop a less invasive way of allowing visual access to NIR light, the UST researchers developed contact lenses based on the same technology used in the injections. That is to say that they embedded gold and sodium gadolinium fluoride nanoparticles doped with ytterbium and erbium ions into the lenses. These nanoparticles exert various effects on light, but the overall impact is that together, they are able to absorb NIR wavelengths and turn them into visible wavelengths in the 400-700 nm range through a process known as upconversion. The particles do this based on their structure and therefore do not need a power source to function.